The present invention relates to a protection apparatus for an IT grid comprising a first and a second live line, to a method and to a power supply system.
Power grids with an electrically isolated ground are used in various technical applications. One possible application for such so-called IT (Isolated Terre) grids is hybrid and electric vehicles.
Although the subject of the present application can be used for a multiplicity of IT grids, it will be described below in connection with IT grids for hybrid or electric vehicles.
In the development of modern motor vehicles, the reduction of the consumption of fuel and therefore also the emission of harmful substances is one of the most important criteria for a development engineer. In order to reduce the fuel consumption of internal combustion engines, these engines can be assisted by an electric motor in hybrid vehicles. In electric vehicles, the internal combustion engine is not assisted by an electric motor but is replaced by the electric motor.
In such hybrid and electric vehicles, a high-voltage energy store, for example a lithium-ion battery, is used in order to store the electrical energy required for the operation of the electric motor. This high-voltage energy is generally transmitted to an inverter via two high-voltage lines, of which one high-voltage line conducts a positive voltage and one high-voltage line conducts a negative voltage.
If such a hybrid or electric vehicle is serviced in a workshop, under certain circumstances the high-voltage lines may be exposed. If, once a service task has been performed on a hybrid or electric vehicle, the high-voltage lines between the battery and the inverter are not properly connected to the inverter, it is possible for a living organism, in particular a person, to touch live parts of the high-voltage lines.
Such a hybrid or electric vehicle is disclosed, for example, in DE 102008001973 A1.